numer- 



THE NECK. 



additional reasons for the comparative infrequency of this operation are furnished by the 

 ous intercommunicating veins which pass downward from the thyroid gland, as the thyroid 

 plexus, to empty into the middle thyroid vein, a tributary of the left innominate vein (see Fig. 24). 

 The inferior thyroid veins take origin in numerous radicles from the isthmus and lateral lobes 

 of the thyroid. Passing downward, the left empties into the left innominate vein, the right into 

 the junction of right and left innominate veins. Frequent anastomoses between the veins of the 

 two sides may result in a rather intricate plexus in front of the lower cervical portion of the 

 trachea. Sometimes this anastomosis results in the formation of a single inferior thyroid vein, 

 which usually empties into the left innominate vein, but may empty into the right. ED.] The 

 line of incision is also occasionally crossed by an anomalous thyroidea ima artery from the arch of 

 the aorta. 



The trachea begins at the lower border of the larynx, where the pharynx ends and the esoph- 

 agus commences. This is at about the level of the sixth cervical vertebra. The trachea bifurcates 

 into the two bronchi within the thorax (see page 114) opposite the fourth dorsal vertebra [or the 

 upper border of the fifth. ED.]; a cervical portion and a thoracic portion of the trachea may there- 

 fore be differentiated, the dividing-line being situated at the first dorsal vertebra. The cervical 

 portion of the trachea may be further subdivided into three parts that beneath the thyroid gland, 

 a short portion above the gland, and a longer portion below it. As the trachea passes backward 

 as well as downward, it constantly becomes further removed from the skin of the neck, through 

 which it may be reached with comparative ease above the thyroid isthmus. Below the isthmus 

 the trachea is covered by the veins of the thyroid plexus and by a varying amount of fat in the 

 jugular fossa. When the head is held erect, the trachea consequently does not pursue a vertical 

 course, but one that is directed from above downward and slightly backward. In children 

 the trachea is covered above the- sternum by the thymus gland, which projects above the upper 

 opening of the thorax to a greater or less extent. 



The esophagus is situated posterior to the trachea and commences opposite the cricoid 

 cartilage about 15 centimeters from the incisor teeth [about six inches. ED.]. It deviates some- 

 what to the left of the median line, projecting slightly beyond the left side of the trachea; 

 esophagotomy for the removal of foreign bodies is consequently best performed by making the 

 incision along the inner border of the left sternocleidomastoid muscle. The skin, platysma, and 

 fascia are divided, the edge of the sternocleidomastoid is drawn to the outer, and the larynx, 

 trachea, and thyroid gland to the inner side. The inferior thyroid artery must sometimes be 

 ligated; particular care should be taken to avoid the inferior laryngeal nerve, which runs in the 

 groove between the trachea and the esophagus. The same incision will serve for the evacuation of 

 those retropharyngeal abscesses which cannot be reached through the mouth, and also for the 

 ligation of the inferior thyroid artery. The esophagus, like the pharynx, is fixed to the vertebral 

 column by loose connective tissue (see Fig. 26) which offers no great resistance to the down- 

 ward extension of retropharyngeal abscesses. Swellings and tumors of the lymphatic glands 

 situated alongside of the esophagus may lead to esophageal stenosis; suppurations in these 

 glands or in the thyroid gland may rupture into the esophagus. The narrowing of the 

 esophageal lumen at the level of the cricoid cartilage is described upon page 115. The 

 esophagus is only loosely attached to the trachea by connective tissue. Running upward to the 



